Plug for underfloor conduit systems



Feb. 21,1933. 7 J. M. G. FULLMAN 1,893,087

'PLUG. FOR UNDERFLOOR CONDUITSYSTEMS Filed Oct. 7, 1950 v 'Z'SheetS-Sheet 1 FIG].

BY ATTORNEYS INVENTOR Feb. 21, 1933. FULLMAN 1,898,087

PLUG FOR UNDERFLOOR bonnun SYSTEMS Filed Oct. '7, 1950 2 Sheets-Sheet 2 1/ INVENTOR BY'ATTORNEYJ Patented Feb. 21, 1933 UNITED STATES PATENT orrlcr.

JAMES M. G. FULLMAN, OF SEWIGK LEY, PENNSYLVANIA, ASSIGNOR TO NATIONAL ELEC- TRIO PRODUCTS CORPORATION, OF NEW YORK, N. Y. A CORPORATION OF DELAWARE PLUG FOB UNDERFLOOR CONDUI'I' SYSTEMS Application filed October 7, 1930. Serial No. 487,020.

This invention relates to improvements in plugs for underfloor conduit systems of electrical distribution. Such systems which are now on the market comprise conduits provided with outlet necks which are adapted to receive plug shaped forms which serve as molds for the concrete in forming the floor. Subsequently when service is desired to be established to the conduit at any point or points in the floor one or more of these plug shaped forms is removed and replaced by a service extension fitting or other current outlet. It has been heretofore proposed to make these plug shaped forms of wood or to form them of cast iron. Heretofore the plugs have been provided with a cavity in the top whlch held a quantity of concrete and in removing the plugs this concrete had to be chipped away from the interior of the plug and this was frequently a tedious and time consuming operation. Previous forms of these plugs also provided for a marker screw which was carried by the plug and which was adapted to be projected up to the floor line to locate the plug in the finished floor. The marker screw also was used for retaining floor covering in place above-the plugs.

The present invention has for its objects the provision of an improved form of plug which in lieu of being made of wood or cast iron as heretofore, is made of stamped metal whereby the cost of construction is mini mized. Cost is a matter of considerable importance with installations of this character since the plugs after being removed from the floor are usually thrown away. Therefore it is desirable to keep the expense of the plugs themselves to a minimum.

A further object of the present invention resides in the provision of a novel construction'of a'diaphragm and a plug whereby removal of the concrete from the plug may be facilitated.

A further object of the present invention resides in the provision of a plug having a diaphragm associated therewith and which diaphragm also serves for the purpose of holding the marker screw in position to and in respect centrally to the plug.

A further object of the present invention resides in the improvement of a plug which may be used in an underfloor conduit system wherein provision is made for providing for the removal of the concrete from the lug by merely striking the concrete carrie by the plug with a sharp hammer blow whereby the concrete is fractured into small pieces so thatitcan be readily removed from the plug. Further and other objects of the present invention will be hereinafter set forth in the accompanying specification and claims and shown 1n the drawings which by way of illustration show what I now consider to be a preferred embodiment of the invention.

In the drawings:

Figure 1 shows a sectional view of plu in assembled relation with respect to a conduit but with the diaphragm shown in raised posit1on preparatory to being placed in the plug;

Fig. 2 shows the concrete molded in positlon and supported by the diaphragm and with the diaphragm retained by the plug;

Flg. 3 1s a detail top plan View taken substantially on line 33 of Fig. 2 but with the concrete not shown;

Fig. 4: shows the manner of removin the plug from the conduit after removal 0 the concrete:

Fig. 5 shows the plug securing floor covering such as linoleum in place; and

F g. 6 shows the plug 'with the diaphragm 1n sltu and the marker screw utilized for securing a floor closure plate in place.

In more detail in the drawings 10 is the condult provided with an interiorly threaded outlet neck 11. The plug will now be described.

The plug is formed of a cup-shaped sheet metal stamping and is generally designated 12. It is provided with a threaded portion 13 to interengage the threads of the necks 11. It is provided with a sloping portion 14 which serves as a seat for the rubber gasket 15 and it is also provided adjacent its top with a flanged portion 16 provided with a recess 17 For facilitating the manufacture of the plug and particularly the threading of the cup-shaped stamping with the threads 13, the bottom portion 18 of the plug is provided with stamped up protuberances or projections 19 which enable the plug to be The diaphragm. will now be described. This diaphragm also is comprised of a sheet metal stamping and is generally designated 20 in Fig. 1. It is provided with a central aperture which is threaded as shown to receive and secure the-marker screw 22 in position therein. The diaphargm 20 is of resilient metal and is of dish configuration as shown and is also provided with a number of notches 23 about its periphery. Inter. mediate the notches the diaphragm has tongues 25 of substantial length. These tongues have a peculiar end conformation which is of such form that the burred edge of the metal diaphragm tongue is adapted to come into engagement with the inside of the flange 16. The flange 16 is'wedge-shaped or tapered and accordingly the diaphragm tongues will bite into the metal of the flange and secure the diaphragm in position when the diaphragm is pressed down into the plug. The greater part of the diaphragm including the unnotched center and the greater part of the tongue portions is centrally depressed so that the point where the tongues join the head body of the diaphragm is situated below the point of contact of the edge of the diaphragm with the inner surface of the plug body. The effect of this arrangement is to cause the tongues to expand as an upward pull is placed upon the diaphragm, thus causing t 1e end of the tongues to more firmly engage with the inside surface of the plug. This feature is of particular utility when the plug is re-inserted in the conduit to close up an opening formerl in use for service in an underfloor system, ecause in such event the lug and its diaphragm are utilized for hol ing down in osition a plate covering the opening in the oor. Such plate is shown in Fig. 6 at 26.

The foregoing arrangement of diaphragm also affords a further advantage. As shown in Fig. 2, the cement 27 within the plug is retained above the diaphragm 20. The size of the slots 23 are such that in laying the floor the cement does not to any great extent, pass through the dia hragm. Some cement passes through the s ots and acts as a lock or bond, but the hollow space below the diaphragm is retained substantially free and clear of cement.

When a plug is desired to be removed with the cement in position in the plug it is only necessary after locating the plug, to strike a sharp hammer blow upon substantially the center of the plug above the diaphragm. This blow will cause the diaphragm to partially collapse and the ultimate result is that the cement is cracked up into comparatively small particles making its removal a comparatively easy operation. It will be understood that the hollow space below the diaphragm permits the collapsing action above referred to. In Fig. 5 the marker screw 22 is shown as cooperating with an escutcheon member 28 which is adapted-to secure a floor covering 29 such as linoleum, in place.

While the invention has been shown and described with a marker screw associated with a diaphragm it will be understood that the use of the marker screw can be dispensed with. It will also be understood that the diaphragm may be used to support a marker screw when there'is no cement present above the diaphragm 20.

It will be understood that the dish configuration of the diaphragm and the tongue arrangement of the periphery with intervening notches provides a resilient construction of the diaphragm which permits it to flex slightly and wedge into the cooperating tapered portion 16 of the cup-shaped plug until the diaphra m is arrested by the shoulders 17 shown in ig. 2. As has been previously explained, the ends of the tongues are comparatively sharp and they accordingly somewhat out into the tapered portion of the cup-shaped flange. It will be understood that while I have preferably shown and described my plug with a shoulder by which my diaphragm may be definitely located with respect to the top of the plug, other means may be used for locating and retaining the diaphragm such as grooves, notches, etc., engaging the rim or arms of the diaphragm which will still remain within the scope of my invention. Fig. 4 illustrates the manner in Which the cup-shaped plug is removed after the diaphragm has been removed in the manner previously explained. In this figure there is shown a plug wrench generally designated 35, having sharp teeth 36 adapted to engage the interior tapered part 16 of the cup-shaped plug and permit the plug to be unscrewed from the cooperating conduit neck 11.

What I claim is:

1. A plug for an underfloor conduit system comprising a cup-shaped plug member with a closed bottom and with a separate diaphragm carried within the plug and adapted to support cement above the diaphragm and within the plug, said diaphragm being of springy material and adapted to collapse upon striking a sharp blow upon the cement thereon whereby the cement in the plug cracks.

2. A plug for an underfloor conduit system which plug is shaped to engage a neck in a conduit wall, said plug comprising a cupshaped member with a closed bottom and a diaphragm carried wholly within the cup below the top thereof and spaced from the closed bottom of the plug for retaining cement and collapsing under a blow, said closed bottom of the plug catching fragments of cement and preventing the same from falling into the conduit when the same is broken up.

3. A plug adapted for removable engagement with an outlet neck of an underfloor conduit, said plug being made of sheet metal and cup-sha ed with a closed bottom and a collapsible diaphragm carried by and wholly within the cup-shaped portion of the plug.

4. A plug adapted for engagement in the outlet neck of an underfloor conduit, said plug having a closed bottom and a recessed portion intermediate the bottom and top of the plug, and a cement supporting diaphra m supported adjacent said recessed portion or the purpose described.

5. The invention set forth in claim 3 in which a tapered wall portion is provided upon the upper interior of the plug for wedging cooperation with the diaphragm.

6. The invention set forth in claim 3 in which the diaphragm is of dished configuration for the purpose described.

7. The invention set forth in claim 3 in which the diaphragm is provided with peripheral notched portions forming intermediate tongue portions which engage the interior of the cup-shaped plug.

8. An underfloor conduit system including a removable hollow plug with a closed bottom with a removable diaphragm carried thereby and therein and spaced from said closed bottom.

9. An underfloor conduit system with a removable hollow plug with a closed bottom, and a collapsible dish-shaped diaphragm carried thereby and therein and spaced from said bottom for the purpose described.

In testimony whereof I hereto afiix my signature.

40 JAMES M. G. FULLMAN. 

